This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-093960, filed Mar. 31, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates to, for example, a radio repeater device which relays between a base office and a vehicular terminal in a communication method of an FDMA method.
The current service system of the radio base station is as follows. Digital and the analog cable signals are converted into the base band which should be made a radio, and is digitized by the time-division and the FDMA (Frequency-Division Multi-Access) method. The multiple radio communication is performed by the number of channels corresponding to the office line.
The radio base station is set through the minute field examination, and the approach line design and the transmission propagation examination. However, the region to which service other than coverage are not received as shown in FIG. 1 exists in the vehicular communication. This region is called xe2x80x9cBlind zonexe2x80x9d.
The radio repeater device enables the communication between the vehicular terminal in the blind zone and the above-mentioned radio base station. Therefore, this radio repeater device is a specification of government-managed or based on this.
The vehicular communication can be called public works, and, naturally, the radio repeater device to which the evil is given since the evil is not given to this communication network to this communication network should not be set up.
However, even if the radio repeater device of the operation between the base stations without trouble at time when it is set up, thereafter, the evil is occasionally caused for the communication network by the change in the environment in the surrounding. This cause will be explained referring to FIG. 2.
To enable the communication between base station 15 and vehicular terminal 25, the radio repeater device has a first antenna 10 (hereafter, called as xe2x80x9cexternal antennaxe2x80x9d for convenience"" sake) and a second antenna (hereafter, called as xe2x80x9cinternal antennaxe2x80x9d for convenience"" sake) set up in the blind zone as shown in FIG. 2. The blind zone is solved by being possible to communicate mutually by sending and receiving wave with each of antennas 10 and 25, and base station 15 or vehicular terminal 25. In addition, this radio repeater device has first and second antenna shared devices 31 and 36, first and second band-pass filters 32 and 37, and first and second amplifiers 33 and 38.
Here, the signal from the base station received by external antenna 10 is input to first shared device 31. Next, only the signal of the desired frequency can pass by first filter 32. Thereafter, the reception signal amplified with first amplifier 22 is input to second shared device 36, the signal is sent to internal antenna 20, and the signal is sent from internal antenna 20 to vehicular terminal 25. The signal from vehicular terminal 25 is received with internal antenna 20, and processed with second filter 37 and second amplifier 38 through second shared device 36 as well as the signal received with external antenna 10. The signal received from first shared device 31 to external antenna 10 with internal antenna 20 is sent to base station 15.
Thus, the communication of vehicular terminal 25 in the blind zone becomes possible.
However, the radio repeater device operates same as the oscillation circuit when the signal from vehicular terminal 25 reaches external antenna 10, as a result, the phenomenon in which the radio repeater device is saturated and oscillates occurs. Therefore, the following disadvantages are occurred. Use of vehicular terminal 25 in the circumference according to the concerned radio repeater device becomes impossible. The relay of other radio repeater devices may be obstructed by generating the noise signal from external antenna 10 or internal antenna 20 caused by the oscillation.
It is necessary to prevent the signal from vehicular terminal 25 from reaching an external antenna not to occur this disadvantage. However, at first, even if it is a structure that the signal of vehicular terminal 25 does not reach an external antenna, the leakage of the relay carrier etc. can happen by a remarkable change in the environment in the surrounding according to the building construction others and the earthquake accident, etc.
As described above, the conventional radio repeater device has the disadvantage that the radio repeater device oscillates because of reaching the signal from vehicular terminal 25 to an external antenna of the radio repeater device.
An object of the present invention is to provide a radio repeater device which solves problem because of oscillation of the radio repeater device caused by leakage of relay carrier etc. etc.
The present invention adopts the following means to solve the above-mentioned problem.
The radio repeater device, which can mutually communicate by relay of a vehicular terminal with a base station, according to the present invention is characterized by comprising: a first antenna to communicate with the base station; a second antenna to communicate with the vehicular terminal; and a repeater section which is connected with the first antenna and the second antenna, and to relay the base station and the vehicular terminal to be able to communicate therebetween, wherein when the first antenna receives the signal from the vehicular terminal, an operation of at least the repeater section is stopped. Here, stop of the operation of the repeater section is performed by stopping a supply of a power supply to the repeater section.
Specifically, the radio repeater device, which can mutually communicate by relay of a vehicular terminal with a base station, according to the present invention is characterized by comprising: a repeater section which can communicate and is the relay of the base station and the vehicular terminal; a pilot signal generation section which sends the pilot signal for the monitor to the repeater section; and a reception controller by which the signal from the repeater section is input, and the operation of the repeater section is stopped at least when intensity is larger than predetermined signals which become standards. Another radio repeater device, which can mutually communicate by relay of a vehicular terminal with a base station, according to the present invention is characterized by comprising: a first antenna to communicate with the base station; a second antenna to communicate with the vehicular terminal; a repeater section which is connected with the first antenna and the second antenna, and to relay the base station and the vehicular terminal to be able to communicate therebetween; and a stop section, when the first antenna receives the signal from the vehicular terminal, to stop an operation of at least the repeater section.
In above-mentioned radio repeater device, preferable manners are as follows.
(1) The pilot signal generation section which sends a pilot signal for a monitor to the repeater section is further provided.
(2) The stop section comprises a reception controller which inputs a signal from the repeater section and stops an operation of at least the repeater section when intensity of the input signal is larger than a predetermined signal which is a standard signal.
(3) The reception controller comprises a comparator which compares the input signal and the predetermined signal and outputs a result thereof and a switch which turns off a power supply of a power supply section which supplies a power supply to the repeater section based on the comparison result.
With above-mentioned configuration, even when the signal from the vehicular terminal leaks to outside and is received by the external antenna, when the signal intensity of the repeater section becomes larger than predetermined intensity (that is, when it becomes a state in which the repeater is saturated and oscillates) by always monitoring the signal in the repeater section, since the operation is stopped, the adverse effect is never caused to other devices. Therefore, it is possible to provide an improved repeater device in the blind zone. Even in a case that the signal is leaked by the change in the environment, since the operation of the repeater device is similarly stopped, the adverse effect is never caused to other devices.
Therefore, according to the present invention, it is possible to provide a radio repeater device which can communicate between the blind zone and coverage without adversely affecting other devices.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.